1. Field of the Invention
The present invention relates to a pressurized container, the body of which contains an assembly of a valve body and of a dished valve-holder part.
2. Description of the Background
Products intended for mass consumption, particularly cosmetic products, are promoted through distribution of free samplers or trial amounts thereof. The sampler must resemble the product on sale as closely as possible, with respect to the formula, the scent, the texture, the galenic form, the packaging, and the outer packaging. For reasons of economy, manufacturers continually seek to produce samplers containing the smallest possible amount of product. Of course, the packaging of cosmetic products in single doses is attractive for travel, as this type of packaging uses very little luggage space.
Although it is known to prepare product packagings for products distribution in pressurized containers, in a small size complying with the original formula, the economic criterion which the sample must also satisfy is presently not being met. This is because even a small pressurized container requires a certain number of indispensable elements in order to function, namely:
a container body, which is a can made of tin plate or aluminum, and on whose walls a lacquer is deposited, PA1 a valve crimped on the neck of the container body via a dished valve-holder part, PA1 and a dispensing means connected to the valve.
Conventional techniques for manufacturing pressurized cans do not afford cans which are small enough to correspond to the volume of a trial dose, which is approximately 3.5 ml to 8 ml. This is because the work of crimping the metal, i.e. crimping the valve-holder dished part on to the container body, on the one hand, and around the valve, on the other hand, which consists in forcing the metal to adopt a desired configuration, in particular to grip on to the valve, is work which can be done only on parts which are sufficiently large. This manufacturing constraint, therefore, dictates the minimum size of the dished valve-holder part, and, hence, the volume of the can which is necessarily greater than a one-use dose.
Furthermore, the operations for fashioning the can are expensive, as is the incorporation of a valve into the can. Unfortunately, this valve is one of the elements which are indispensable to the operation of the pressurized container.
In order to solve this problem, use of a can made of a thermoplastic instead of metal has been envisaged. However, this approach is also very expensive since the high internal pressure caused by the gaseous propellant necessitates the use of very thick plastic in order impart sufficient rigidity. On the other hand, the crimping of the valve to the neck of the can requires this neck, and this valve, to have a special shape. It is, therefore, necessary to use a valve which is designed for external crimping, and which is, therefore, more expensive than a standard valve. External crimping has to be carried out on a perfectly even surface, which is to say a surface with no trace of parting line or mould release line. Thus, the cans must be manufactured by an injection blow-molding technique, which is expensive when a large number of units are produced.
Conventional pressurized devices consist of a container body on which a cap may be fitted; crimped to the neck of this container by means of a dished valve-holder part is a valve; a dispensing means is connected to the valve; the container body and the dished part define a reservoir cavity; the valve consists of a valve body, of a valve-control stem which passes through the valve body, of a seal, and of a return system which presses the valve-control stem against the seal, with all of the above being held in place by the crimping of the valve-holder dished part; the valve-control stem is surmounted by a push-button. Arranged in the container body are a product to be dispensed and a propulsion means therefor.
The propulsion means may be a compressed gas in direct contact with the product in the container body. In this case, a dip member is fixed to the valve. When it is not desired that the product be in contact with the gas the gas and the product may be separated by a flexible bag or using a piston. When a flexible bag, is used, problems often arise regarding compatibility with the formula and solidity of the material of which the bag is made. The bag must, at once, be flexible and leaktight. When a piston is used for separating the gas from the product, problems are encountered because the seal along the contacting surfaces of the piston and of the internal wall of the container body. Furthermore, in both cases, the gas-filler orifice must be distinct from the one for the formula, i.e. filling with gas often takes place through an orifice situated at the bottom of the container and which is then closed off by a rubber bung. This configuration implies repeated operations during manufacture, namely opening the gas-filler orifice, installing the bag or the piston, and fitting the bung. It is also expensive because of the complexity of the filling process, i.e. requiring filling first with product and then with gas.
EP-A-0561292 discloses dispensing devices using, as propulsion means, a closed-cell cellular material. A gas is held captive in the cells of the cellular material. This document describes a device in which the product is placed in a flexible bottle, inside the container body. The cellular material is placed in this container body in contact with and on the outside of the flexible bottle. The cellular material is connected to a thumb wheel. Before the valve is actuated using a push-button, energy must be stored in the cellular material by actuating a thumb wheel. The gas contained in the cellular material is then placed under mechanical pressure and this pressure is transmitted to the bottle and to its contents. Thus, by actuating the valve, the product can then be dispensed.
However, such a device has numerous drawbacks. For example, this device has a large number of component parts, which component parts require a very fine compatibility (screw threads, leaktightness) and are, moreover, sophisticated. Consequently, such a device is quite very expensive. The storage of energy by mechanical compression of the cellular material takes place in small quantities and the user must turn a thumb wheel in order to store up the energy corresponding to approximately one dose before actuating the push-button. The required two-part action makes the device complicated and not very attractive for consumers with little available time. The bottle in which the product is contained has the shape of a bellows and so, even if it is compressed as much as possible under the action of the cellular material, such a bottle cannot be completely emptied and a low restitution ratio will be obtained.
When energy is stored in the element made of cellular material by turning the thumb wheel, a strong osmotic pressure is created across the wall of the bottle. Thus, the wall of this bottle, subjected to an alternating movement through the mechanical action of the cellular material, is weakened by excessively frequent use. The same problem of compatibility of the product with the wall of the bottle is encountered with this device as is encountered in the case where use is made of a flexible bag for separating a gas from the product. Furthermore, if the user inadvertently exerts too strong an action on the thumb wheel, the cellular material will be subjected to a pressure which causes the cells containing the gas to burst and will irreversibly damage the device. Finally, such a device does not allow the bottle to be filled with product through the valve, pressurizing the cellular material, because this mechanical compression will also result in a bursting of the cells, rendering the device unusable.